Ensure github-plugin can auto register hooks with enterprise git, remove
the condition which only fetched GitHub instances where the site was
official github site, otherwise returned empty collection
caught an NPE when calling the GithubProjectProperty.projectUrl, returned null in the catch in keeping with the if(tcc.projectUrl == null) check
adding a logging message if the projectUrl cannot be found in the existing config
Adds a CrumbExclusion for the GitHub WebHook page

The GitHub webhook endpoint should not be protected by the CSRF protection
built into Jenkins. This commit adds a CrumbExclusion filter so that the endpoint
created by c.c.j.GitHubWebHook is not protected using the CSRF crumb protection scheme.

Bumps Jenkins API version minimum amount required for CrumbExclusion.
removing the try/catch and replacing with separate checks for JSON binding and the existence of the project URL
Tightens exception handling for Github Webhooks.

Checks to see if the Github Webhook request being processed is actually
of type 'push' before trying to process the request payload. The structure of
each type of Github Webhook differs and processing will fail.

Improves exception message when payload is not found and urges the
client to check the payload version on the Github Webhook to allow
easier debugging.
Merge pull request #40 from hubba/master

Tightens exception handling for Github Webhooks.
doc improvement.
[FIXED JENKINS-18710] merge pull request #31
Requiring 2.0 now

Git plugin 2.0 is here and it's better that this plugin is built against
a modern version of the Git plugin
[FIXED JENKINS-20201]

I'm actually unclear why bindJSON can return null at all.
But I'm not going to let that mystery block users.
Merge pull request #34
[FIXED JENKINS-20140] Merge pull request #35